Psoriatic arthritis: a systematic review

Psoriatic arthritis is an inflammatory rheumatic disorder of unknown etiology occurring in patients with psoriasis. The Classification Criteria for Psoriatic Arthritis study group has recently developed a validated set of classification criteria for psoriatic arthritis with a sensitivity of 91.4% and a specificity of 98.7%. Three main clinical patterns have been identified: oligoarticular (≤ 4 involved joints) or polyarticular (≥ 5 involved joints) peripheral disease and axial disease with or without associated peripheral arthritis. In this context distal interphalangeal arthritis and arthritis mutilans may occur. According to other reports, also in our centre, asymmetric oligoarthritis is the most frequent pattern at onset. Axial disease has been estimated between 5% and 36% of patients. It is characterized by an irregular involvement of the axial skeleton with a predilection for the cervical spine. Recurrent episodes of enthesitis and dactylitis represent a hallmark of psoriatic arthritis. In around 20% of cases distal extremity swelling with pitting edema of the hands or feet is observed. Unilateral acute iridocyclitis, usually recurrent in alternate fashion, is the most frequent extra‐articular manifestation, and accelerated atherosclerosis is the prominent comorbidity. The clinical course of peripheral and axial psoriatic arthritis is usually less severe than rheumatoid arthritis and ankylosing spondylitis, respectively. Local corticosteroid injections and non‐steroidal anti‐inflammatory drugs are recommended in milder forms. Sulphasalazine and methotrexate are effective in peripheral psoriatic arthritis. Recent studies have provided evidence on the efficacy of anti‐tumor necrosis factor‐α drugs to control symptoms and to slow or arrest radiological disease progression.